JPH06500222A - Device for focusing optical imaging systems - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Focusing optical imaging system Method and apparatus for The present invention provides an optical imaging system by step-by-step adjustment of the distance between the object and the objective lens. Regarding the method and device for focusing, the relevant adjustment is subject to the above. This is done until the maximum value is obtained for each detected sharpness value of the object. do.

Method and Apparatus for Focusing an Optical Imaging System When the imaging system focuses an approximately two-dimensional surface, e.g. It can be used in any case where extremely precise focusing is required on the original image. be. Furthermore, the preset focusing state can be optimally adjusted when refocusing. The method and device can be used with particular advantage if the conditions are met.

For focusing of optical imaging system and for detecting focusing state Methods and devices are known for a wide variety of application areas and embodiments. Object (this can be two-dimensional or three-dimensional and of low or high contrast). Various problems arise depending on the type, time requirements and method of implementing the process. Various measures have been proposed for the field. Federal Republic of Germany Patent No. 314118 Depending on the device for measuring the focusing state of an optical imaging system known from No. Detection of the flushing condition of the system is performed as follows. In other words, short-term objective lens The focusing condition is adjusted so that it is almost unaffected by image changes caused by The purpose of this is to ensure that the detection of the This requires a number of steps. A memory and evaluation circuit has been proposed for special problems using

Proposals have been made for the area of self-focusing microscopes. According to the method, at least each pixel of a three-dimensional original image is connected to the adjacent point using a sensor. form the difference (brightness (luminance)), add the error for all pixels, and subtract it. Next, adjust the distance between the object and the objective lens, form the above sum again, In this case, select the following interval, i.e., the interval that maximizes the sum of the memberships. Select (German Patent Application No. 3340647).

The problem forming the basis of the invention is, in particular, the knowledge of the expected focus area. A predetermined focus value can be corrected quickly and reliably, and the object-object lens distance is optimized. We present a method of the type mentioned at the beginning, which is optimally tunable with appropriate sharpness values. It is about providing.

Furthermore, in a device of the type mentioned at the outset, it is possible to simplify the operation and thus the practical application. , perform automatic focusing with high precision and great reliability, thereby for quick adaptation to changed originals and possibly changed diameters of the image support drum. It allows for adaptation. In particular, focus on operational preparation equipment and can be transmitted to the scanner, in which case both devices do not need to have high accuracy. This is what you do.

In order to solve the above problem, a method having the constituent elements specified in Claim 1 is proposed. proposed.

Due to digital processing, there are no relatively small differences such as soil removal for precise adjustment. However, differences can also be reliably processed and stored. At that time, the optimal evaluation is price is possible. Large differences are valued higher than small differences in sum formation. The sharpness From the degree value, which of the belonging focusing states is better? It also becomes clear in which directions further improvements can be made. The focuser Above the maximum value of sharpness, the sharpness value becomes smaller and the evaluation according to the invention and adjustments are made subsequently. Desired optimal state of focusing state For the approximation of , steps that are initially relatively large and later become small may be chosen (difference-until the sharpness value falls below a predetermined limit value). When it goes down like that, focus This indicates that the operating condition has reached its optimum value with a reasonable approximation. Advantageously the sharpness of one scan line for the section scanned for detection of degree values. A small portion (which is approximately 512 pixels long, for example) is used. image A special selection of parts (regions) is only necessary in special cases, that is, The method and apparatus are designed to generally easily capture images. It is designed so that the section in the middle can be selected. At that time, minute changes Image areas with texture (e.g. material patterns) have proven to be particularly advantageous. ing. Black surfaces on film originals also work well, since the film is This is because focusing can be performed on the lum particles.

This section of the scan line is approximately 15 mm long for reflective originals. or, in the case of a transparent original, the length of IQim. Of course, the data (number Deviations from this value) are possible within the framework of the invention. When manually adjusting the sharpness value, are as many sufficiently coherent images as possible within the area scanned for the detection of the sharpness value in question. There should be image details that can be distinguished from each other; With a correspondingly constructed device, the evaluation of the original painting as an object can be carried out using the reference standard of the human eye. This is because it is done specifically and independently of the time.

In practice it is clear that due to the formation of sharpness values the brightness and brightness of the red channel ) signal is suitable, because the cyan color separation derived from it However, when using image originals (original images) that are scanned for image reproduction in cross-printing, This is because it has the greatest impact on impressions. The magenta decomposition is also important, while the yellow Color (Y)-separations are of secondary importance.

The scanning is advantageously carried out under a scanning aperture of the imaging system, which means that a small Details can also be resolved and detected by scanning with changes in their brightness or brightness. It can be done. In this case, the scanning is carried out under a predetermined small depth of focus of the imaging system, in other words: This should be done with the objective lens fully open, thereby slight changes in the focusing state, especially changes in the distance between the original image and the optical system. It seems that even small changes have a significantly large effect or influence on the sharpness value. It is better to make it .

The focusing state uses at least one motor, e.g. a step motor. can be controlled by A step motor has a significantly smaller step width and The pre-adjustment or presetting can be carried out steplessly and continuously. Furthermore, completely A piezo drive unit is used for adjustable movement operation that can operate steplessly and quickly and flexibly. You can also have them do it.

Advantageously, the focusing state is readjusted in steps of 0.5 to 0.25 mm. In particular, the readjustment step when approximating to the optimal state is 2 μm (0,000211) can be made as small as

Before the first detection of the sharpness value, the focusing state of the imaging system is preferably set to a predetermined initial value ( This may for example be located near the expected value for the sharpness value). obtain. Such adjustments to certain initial values may be made manually, e.g. under observation of the scanned image. can be performed, thereby eliminating the need for relatively long adjustments in unsharp conditions to save time. It can be. Adjustment to at least approximately maximum sharpness at different locations in the image alignment can also be performed, and the coordinate values of each of those locations are recorded. The focusing state may be readjusted during scanning of the original image. It can be made so that This can be important when, for example, supporting The body roller may be eccentric or the surface to be scanned may not be exactly straight. The position of the surface of the original image is scanned due to some sagging (hanging). may have significance when changing in the desired area.

The above can be taken into account by automatic readjustment of the focusing state.

Next, the present invention will be explained in detail using figures.

FIG. 1 partially diagrammatically shows the cooperating components and signal variable stages in question, and also shows Shown in association with the circuit stage, Figure 2 shows the processing section for creating and evaluating sharpness signals in more detail. show, Figure 3 shows the characteristics graphically.

The scanning drum 10 of the device 11 for measuring (detecting) the focusing state is It is rotatable about a shaft 12 (its bearing is not shown), and has the illustrated mark on the left end surface. It is driven by the motor 13 in the RY rotation direction as shown by the arrow. #1.2 other end A coordinate generator 14 attached to the line sends a coordinate signal to the line 15, and the coordinate signal is The original image 17 in the Y direction extending from the bottom to the top on the front surface of the scanning drum 10 The scanning window above], corresponds to scanning within 6. At that time, depending on the above scanning window, playback ( (Restoration, reproduction) The area of the original image to be restored is set.

In front of the scanning drum is the X direction (which extends parallel to axis 12 from left to right). ), the feed slide 18 is arranged schematically, i.e. in particular without mechanical bearings being shown. The slide is connected to the shaft 12 using a spindle 20 by a motor 19. and is moved along the scanning drum 10 in a parallel direction. Coordinate speaker 21 is track 2 The X coordinate signal corresponding to 2 is sent.

A charging scanning mechanism 25 is arranged on the feeding slide 68, and this scanning mechanism The motor is guided on sliding rods 26 and 27 at the same distance from the surface of the scanning drum 10. It is shifted (moved) in one Z direction using a spindle 29 driven by a motor 28. It can be done.

The beam cone (cone beam) 30 belonging to the scanning mechanism 25 is in a focusing state. , the pixel of the original image 17 (which is located on the scanning line 32) within the scanning window 16 31 brightness). The R, , G, and B obtained at that time are The corresponding color measurement value signal is sent to the A/D converter 34 via lines 33'', 33g, and 33b. This converter is supplied with the data for subsequent call processing via a word shaper stage 35. Sends out digital color data R, G, and B.

The color measurement value signals R, G, and B on the lines 33r, 33g, and 33b are A/D converters. 34 into 12-bit color data, and a signal shaper stage 35. The image is processed, for example, logarithmized and subjected to white balance processing. On the output side The transmitted color measurement value signals R1G, B are further processed, e.g. for color correction. and then supplied to a recorder (not shown) or other recording equipment. It will be done.

The scanning window 16 on the original image 17 defines the coordinates for the area to be scanned and In the axial direction, the left image is indicated by Xl, the stone statue is indicated by ), the lower edge is indicated by Yl and the upper edge is indicated by Y2.

small in scanning mechanism 25 for desired focusing to maximum image sharpness. a scanning diaphragm is provided in the beam path, with the scanning diaphragm e.g. The scanning point 3] is generated. The above scanning diaphragm is used as a color measurement value signal for subsequent processing. In order to adjust R, G, and B, it can also be used for white balance adjustment that is required during a standby period.

Scanning aperture (job aperture) for scanning, in particular for the production of color separations lens) is determined by the scale calculation, and is generally a scanning aperture for focusing correction. It's bigger. The above-mentioned white balance tone is achieved by the above-mentioned aperture (Jobbler+de). adjustments will be made.

To adjust the focusing condition, scan points 31 are used to scan sections of the original (the corresponding The section (corresponding to the central portion 36 of the object line 32 in FIG. 1) must be scanned. , at the center of the section 36 at the scanning point 31 with the coordinate value X3. Y3 can be associated. The coordinate values may be input to the central control unit 38, where the center On the input side of the control unit there are on the one hand a line 22 with the value of the respective X coordinate and a respective A track 15 having a Y coordinate value of is the motor control for the X-adjustment by the motor 19 to the desired value X3 via the output line 39. The controller 40 is controlled.

Signal processing is performed via the line 41 by the output for the color data R of the signal shaping circuit 1 stage 35. A logic stage 42 is controlled, and the output of the signal processing stage is transmitted through a calculation stage 43 and a line 44. Then, the motor control section 45 for the four force song control motor 28 is operated.

The focusing is performed from the input side Z3 to the control unit 38, the line 46, and the motor. It is set to the initial value via the control unit 45 and the motor 28. The above value is determined by some method. It may be set by memory. It is also possible to manually It is also possible to perform adjustment operations, and at the same time an image-playback device (not shown) The sharpness of the image is determined visually.

Via a connection 47 from the central control unit 38 to the memory control unit 48, The Y coordinate generator 14 and the predetermined coordinate value Y3 of the point 31 are continuously generated as the drum rotates. a region defining a section 36 for sharpness detection; A range signal 49 is also supplied to the unit 48.

The signal processing stage 42 is then controlled by the memory control unit 48 as follows. In other words, only the portion of the color data corresponding to the section 36 is calculated. It is controlled so that it is guided to step 43. The memory control unit 48 has the required Define the write clock and write command.

The color data R used corresponds to the drawing length of lQim in the area of coordinate value Y3. The drawing line 32 has 512 drawing points. The above picture points are stored in the picture line memory of the signal processing stage 42. written. If the height of the scanning window 16 is smaller, The number of pixel points is also relatively low (selected).

The image line memory in the signal processing stage 42 has a capacity of, for example, 512×9 Bits.

Since the color data has 12 bits, only the high-order bits are stored in the drawing memory. transferred inside. The drawing memory in the call processing stage 42 is preferably a FIFO memory. Yes, the data is input sequentially in the memory, and the first input is the same and the highest. The first time it appears again on the output side. The color data R is then supplied to a calculation stage 43, which Then, the difference of the color data R of one pixel with respect to the color data of the preceding pixel is formed and is squared. , and the squared values so obtained are added, with the squared values is formed over section 36 to form the sharpness value.

Via the motor 28, the focus can be adjusted by a predetermined value dZ in any direction via the spindle 29. shifted in the direction. The magnitude of dZ is determined by the change signal supplied via the line of the calculation stage 43. The signal is supplied to the motor control section 45 via the line 44. . A new sharpness value is then formed and it is determined whether the value is greater or less than the previous value. Accordingly, a positive or negative change signal dZ is supplied to the motor control unit 45, where , a relatively large shift towards sharpness takes place. Above the maximum sharpness value , the adjustment value dZ can be decreased, for example from initially 0.3 ml to 0.1511 can be done. Optionally, focusing can be repeated in different directions (at least until approximately maximum sharpness is set).

The course of sharpness as a function of the focusing degree Z has a dome-like course shape; The top of the curved profile corresponds to maximum sharpness. The characteristic curve has three measurement points. by one circle in the case of , and quadratic or more in the case of more ( It can be approximated (with respect to the vertical axis) by a higher order parabola. Therefore the best reading At least one other measurement value located before and after it is also detected. In this case, the calculation program determines the apex of the approximate curve and You can do some research. In this case, of course, when using a step motor, it is generally only an approximation. Only specific adjustments are possible. Below, the maximum sharpness is calculated for the point or distance interval below. The method of the present invention for setting and detecting approximate curves will be explained in detail.

The setting of one image line in the center of the scanning window 16 for optimal focusing state detection. It is possible to detect the corresponding sharpness not only in the section 36 but also in any area of the pond. It is. In particular, if the surface of the scanning window 16 is located precisely on the cylinder surface with respect to the shaft 12, If not, or if the scanning drum 10 is mounted somewhat eccentrically on the axis , or the scanning drum 10 does not exactly correspond to the cylinder surface, but is located somewhat centrally. If sagging occurs, at least one other location of the scanning window 16 is used for focusing (sharpening). It is advantageous to carry out a temperature value detection). In that case, the scanning drum 10 should be taken into account. Especially when fixed on one side, there may initially be some slack at the opposite end, but this phenomenon can be overcome by self-centering after a short start-up time (start-up time). Is Rukoto. At that time, the so-called detection against the focusing device! ! (Setsuti The value Z can be stored in one of the circuit stages 42, 43 or 48, where it is The focus can then be stored for some readjustment during scanning of the original image.

In some cases, the motor 28 may be supplemented with a piezo drive, thereby achieving continuously variable speed. , possibly at relatively high speeds, i.e. even during one drum revolution. It is preferable to make it possible to do so.

2 substantially corresponds to the signal processing stage 42, calculation stage 43, and memory control unit 48 of FIG. The color data of the red (R) channel indicating the circuit stage that functions as supplied to The interval stage 54 receives the coordinate signal from the line 15 and the line 47. This is controlled by the Y3 coordinate value of the point 31 and the Y area signal 49. Railroad 55. 56 supplies control values to a circuit stage 53 which receives the color data of the scan line 32. is passed through to the memory stage 57 from the beginning of the section 36 to the end thereof, and The control value is stored there. The stored color data R is recalled by the comparison stage 58. Then, the difference signal is formed between the color data R of successive pixel points, and the difference signal is formed on the line 5. It is connected via 9. It is squared at the squaring stage 60.

The squaring value thus obtained is passed from the squaring stage 60 via a line 61 to the summing stage 6. 2, and in the addition stage, the squared value of the difference signal from the line 61 is added to a predetermined number of are added for the pixel points (the predetermined number being given by the interval stage 54). It will be done.

The sum so obtained produces the sharpness signal of the scanned section in question. and the sum is supplied to the sharpness price 64 at the end of the addition interval; It is fixedly held there. The supply of the sum in question is made. Via the control unit 54 , a ready signal is provided to switch stage 53. This causes the switch stage 53 to run. When the next color data R is sent out from the scanning mechanism 25, it belongs to the section 36 again. The relevant color data area is accommodated and transferred to the memory stage 57. Sharpness from 64 The values are provided to a second comparison stage 66, which determines the sharpness of successive scans. Values are compared. The positive or negative difference value thus obtained is transmitted via line 67. , are supplied to the evaluation stage 68. Depending on whether the difference value is positive or negative, the corresponding positive or A negative adjustment movement value dZ is supplied to the motor control unit 45 via the line 44. first One predetermined value that causes the adjustment movement in relatively large steps to dZ is set. When approximating the sharpness value to the maximum value, the difference between the sharpness value and the sharpness value becomes smaller. Then, the following switching takes place in the evaluation stage 68, i.e., the adjustment The movement is performed with a relatively small value dZ, where: The changed value can be previously input from the outside using the change code 50. Everything All stages are controlled by a central control unit 69.

In the framework of the invention, the individual functions, in particular storage and comparison, are described in the above exemplary embodiments. Functional operations can be grouped together in different ways than those described above.

To perform focusing or focus correction (the focusing or focus correction Adjust the distance between the scanning original image and the objective lens so that maximum sharpness is achieved. ), according to the invention, a special A suitable adjustment or correction method is provided. However, this example is based on is already within the scope of preparing the scanning drum for operation during the preparation of the scanning process in a separate device. an optical system (wherein each of the scanning drums is provided with at least one scanning original); This means that adjustments are being made for this.

The relevant preparatory value for the optical system as the focus value is the entire data set (this (including other adjustments to the device). The advantage of this is that This minimizes the preparation time of the scanning device, and as a result eliminates any adjustments or corrections described below. Optimal focusing is achieved when the process is performed in a small number of steps.

Based on the start value detected during operation (work) preparation, the objective lens and target A sharpness value is calculated based on the distance between objects. At that time, the relationship between the objective lens and the object The distance between the The sharpness is adjusted step by step, and then the left and right side of the predetermined interval value on the virtual sharpness curve. A corresponding sharpness value is determined for each of the two side spacing values. 3 above Based on the following experience, the sharpness corresponds to Regarding the adjustment range of the object lens, it can be distributed according to mathematical properties, e.g. according to a parabola. Based on the experience of This can be seen as the following three points. Corresponding characteristic curves can be calculated using standard mathematical methods. In other words, its functional relationship is found. Then sharpness - maximum value occurs Spaced enclosure. At that time, there is no need to set a specific sharpness value - maximum value, and This is because only the corresponding spacing value for the objective lens is the intended value. So For the control (monitoring), the interval value is used, the sharpness value is determined, Then, it is checked whether the sharpness is greater than the sharpness values of the three starting points. It will be done. If it is such a large value, it is confirmed that the maximum value can be successfully determined. (Figure 3). Otherwise, the adjustment process (technique) is aborted.

The best sharpness value so determined is already located within the region of the maximum sharpness value. . This is due to the fact that the original image is two-dimensional, i.e. has a substantial thickness difference. The alignment of the sharpness values with respect to the movement area is adjusted based on the scanning of the original image, which is not Object lens - Approximate curve with respect to spacing (this is approximately a downwardly opening parabola or hyperbola) This is due to the fact that it is distributed along the following lines:

In this case, the characteristics of the sharpness value regarding the adjustment movement area of the object-objective lens-distance are considered. There are mistakes. In this case, only the fewest possible steps or procedures can be achieved It is only necessary that the value is detected, and this detection can be done in a few steps. , since the deviation is in any case only slight based on the aforementioned effects. This is because it only occurs in

It has become clear that the curve V that produces the sharpness value S is the relationship between the objective lens and the object. can be approximated by a downwardly opening parabola for the adjustment value of the interval between . Therefore The two spacing distance points R1 and R2 are the focusing points with the best sharpness values up to that point. is set for each adjustment direction based on the distance value or interval distance point, i.e. for each adjustment movement direction. 1 step with a large step width of 0.1511 from the interval distance point Ro A group is selected. Certainty - two points within a given possible adjustment region as a reference measure is checked, thereby ensuring that: It is thus ensured that the objective lens is adjusted into the original image and does not cause damage. Current If there are no two points within the predetermined adjustment region of the step width, the step width will be adjusted accordingly. It is now determined whether all points are within the predetermined adjustment region vS. Will be checked. If such a sharpness value SL, 32 exists, two It is searched under predetermined interval distance points R1 and R2. their resulting sharpness Value S. 2 S, S2 is a mathematically detectable approximation curve for the characteristic curve V. It is regarded as a point of the curve and is determined by means known per se. Then the hyperbola or radiation The distance value R-e to be associated with the vertex of the object line is determined. At that time, at the corresponding vertex The adjustment value of the distance between the object and the objective lens corresponds to the following adjustment value, immediately In other words, at that value, there is a very high probability that the maximum sharpness value also corresponds to the adjusted value. Ru. This relationship is shown qualitatively in Figure 3, where the objective lens Object-spacing is the distance from the axis of rotation of the scanning drum on which the object is mounted. This is set as the distance radius R between the object lenses.

In that way, the adjustment value can be set and adjusted with the maximum sharpness value. . Overall, the sequence can be characterized as a chronological sequence of application of the following procedural steps: obtain.

a) Detection of the first sharpness at a predetermined distance interval between the object and the objective lens Method step b) First (larger) step width for each step below By varying the above-mentioned distance intervals and detecting the sharpness value, the overall 3 a procedural process resulting in two sharpness values; C) object-objective-as a function of the sharpness value for the adjustment area within the interval The above three points are the points of the second, third or higher order mathematical characteristic curve. A procedural process that deals with sharpness; d) Geometric or mathematical steps known per se in the form of functional expressions of characteristic curves; a procedure for determining the coefficients of the corresponding characteristic curve by means of a step-by-step procedure; e) For detecting the adjustment value of the object-objective lens-distance that is associated with the vertex. A procedure for locating the apex of the characteristic curve, f) Procedure for setting the above detected adjustment values It is equipped with the following.

By the above means, it is possible to optimally focus the objective lens in a small number of steps. Ru. The present invention is based on the above-mentioned remarkable knowledge, that is, in Sosai's original picture, For example, unlike problems in focusing a camera or microscope or other equipment, The sharpness values are distributed along the detectable proximity region in advance, so that Substantially saves additional processes and checking measures that would otherwise be required I can hear it.

Advantageously, it is also possible to take the following steps: The sharpness value (which constitutes the maximum sharpness value) is higher than all other previously determined sharpness values. Further measures are taken to introduce a check criterion scale to check whether the This can be done. This ensures that the optimum sharpness value is adjusted. The following measures may be taken to increase the reliability of the process: Method of detecting the sharpness value at the two interval points according to the above procedure step b) After performing , first, the two sharpness values are detected by the above procedure (Na). It is checked whether the first sharpness value S, which is In case of non-fulfillment of the requirements of step b) Perform the procedure in large steps and, if not, This allowed the continuation of the process.

In addition, the following measures may also be taken: Method of detecting the adjustment value After performing the procedure, first determine the associated sharpness value S□, and , the two sharpness values at the two interval points P1゜P2 according to procedure step e) and Check whether the sharpness value according to a) is smaller than the belonging sharpness value, and If the requirements are not met, the procedure or process will be interrupted and an instruction to interrupt will be triggered. and, if not, the continuation of the process or procedure. I made it.

August 19, 1993

Claims (17)

[Claims] 1. Adjustment of the optical imaging system by stepwise adjustment of the distance between object and objective A focusing method, in which the stepwise adjustment involves a respective inspection of the object. For the sharpness value that is generated, the method is used to obtain the maximum value. and has the following procedural steps a) to j), namely: a) Detection of a first sharpness value under a predetermined distance interval between the object and the objective lens method step b) for each step with a first (larger) step width By varying the distance interval and detecting the sharpness value, there are three a procedural process that yields a sharpness value of c) as a function of the sharpness value for the adjustment area in the object-objective distance; The above three sharp points are the points of the second, third or higher order mathematical characteristic curve. A procedural process for handling sharpness values, d) Geometric or mathematical steps known per se in the form of functional expressions of characteristic curves. a procedural step of determining the coefficients of the corresponding characteristic curve by means of a procedure; e) By detecting the adjustment value of the distance between the object and the objective lens, which is associated with the vertex. a procedure for finding the apex of the characteristic curve; f) Procedures for setting the above detected adjustment values. A method characterized by comprising: 2. Method steps for detecting the sharpness value at the two interval points in question according to step b) above. After performing the process, the two sharpness values in question are first detected according to step a) above. It is checked whether the sharpness value is less than the first sharpness value, and here In case of non-satisfaction of the condition, a new start according to step b) is performed with the increased first size. step width and, if not, the steps in the process. The method according to claim 1, wherein a continuation is performed. 3. After performing the method of detecting the adjustment value belonging to the vertex in question according to the procedure step e) First find the associated sharpness value and then set the two interval points in question according to step e). and whether the sharpness value according to a) is smaller than the associated sharpness value. and suspending the procedure or process if the requirements are not met. and trigger an interrupt instruction, otherwise the process or procedure 3. The method according to claim 1 or 2, wherein the continuation of the method is carried out. 4. For the generation of sharpness values in the original image (17) as the object a) The image signal value representing the focusing state is calculated from the photoelectric dots on the original surface (17) and Generated by line scanning, b) Image signal value - difference between the image signal value of each surface point and the image signal value of the adjacent pixel c) squaring the image signal value difference and adding the squared image signal value difference; and the sum value formed at that time constitutes a sharpness value. The method described in any one of the following. 5. In order to detect the sharpness value, one scanned line of the original image (17) is simply Claim 1 wherein only the plane image signal value of one section (36) is used. 4. The method described in any one of paragraphs 3 to 4. 6. Claim 1, wherein said section (36) has a length of approximately 512 pixels. 5. The method according to any one of 5 to 5. 7. The section (36) is approximately 15 mm long in the case of the reflective original (17). 7. A method according to any one of claims 1 to 6, characterized in that: 8. The section (36) is approximately 10 mm long in the case of the transparent original image (17). 8. A method according to any one of claims 1 to 7, characterized in that: 9. When scanning the colored original image (17), the color signal of the red channel is used to detect the sharpness value. 9. A method according to claim 1, wherein the method is adapted to be used. 10. The high-order bits of the digitized image signal value are used to detect the sharpness value. 10. The method according to claim 1, wherein the method comprises: 11. The scanning is performed under a small aperture of the imaging system (25). The method according to any one of claims 1 to 10. 12. The scanning is performed under the minimum depth of focus of the imaging system (25). A method according to any one of claims 1 to 11. 13. The focusing state of the imaging system (25) is controlled by at least one stepper motor. The person according to any one of claims 1 to 12, wherein the change is adjusted using Law. 14. The focusing state of the imaging system (25) is changed using a piezo drive unit. 13. The method according to claim 1, wherein the method comprises: 15. The focusing state of the imaging system (25) is determined before the detection of the first sharpness value. Any one of claims 1 to 14, wherein the initial value (Z3) is reset. The method described in Section 1. 16. The initial value (Z3) is determined in a separate device (operation preparation device). 16. A method according to any one of claims 1 to 15. 17. Before the original scanning of the original (17), a small amount of Adjustments are made to approximately the maximum sharpness in both cases, and the coordinate values of each location and the attached photo are adjusted. - The casing state is memorized and the original (17) is scanned during the original scanning of the original (17). 7) When the original image area around the relevant part is scanned, the above focusing pattern will appear. Any one of claims 1 to 16, wherein the state can be automatically adjusted each time. The method described in section. 18 Optical convergence can be achieved by adjusting the distance between the original surface as an object and the objective lens. A device that performs focusing of the image system, which focuses the dots and lights of the original image (17). Photoelectric scanning is used to generate a surface image signal representing the focusing state by scanning in a circular pattern. It has a head (25) and an adjustment device (28, 45) for the objective lens. in a device that connects the scanning head (25) and the adjustment device (28, 45). A connected signal processing device (42, 43, 48) is provided, and the signal processing device of a plurality of pixels in at least one section (36) of a line. For multiple image signal values, difference values for the image signal values of adjacent pixels are formed respectively. is squared, the squared difference value is added and used as the sharpness value, and Then, the sharpness value of one scan of the original image (17) and the changed focus synchronization are calculated. the sharpness values of one subsequent scan performed under , from the obtained sharpness difference, the focusing state of the above imaging system is calculated. A correction signal is derived and supplied to the adjustment operating device (28, 43), where it is Then, using the correction signal, the focusing state is changed by only one predetermined step. The sharpness value is readjusted in the direction of increasing, and the focusing state is readjusted as described above. The adjustment is configured to be repeated until the instantaneous sharpness value-difference is below a predetermined limit value. A device characterized by: